CVE-2026-103922: Capacitor Android and iOS: remote content can be loaded at the app origin via the internal HTTP proxy path

Capacitor's navigation guard checked only the host and scheme of a target URL. The internal proxy path lives on the app's own origin, so navigating to it counted as in-app navigation. Loading it as a document made the native layer fetch a caller-specified URL and return the body to the WebView at the app's origin. Script in that response gets localStorage, cookies and every native capability exposed through the app's registered Capacitor plugins.

The proxy handler was served whether or not the CapacitorHttp plugin was enabled, so apps that never turned it on were affected too. Android and iOS are both affected.

The attacker needs the victim to activate a link inside the app's WebView. Apps that render user-controlled or unsanitized links, such as chat messages, comments or rich text, are the delivery surface. The attacker then runs script with the app's trust and can reach device features through its plugins, such as files, camera, or stored tokens, depending on what the app registers. The vector rates confidentiality and integrity impact as high, with changed scope.

Affected, for @capacitor/android, @capacitor/ios, com.capacitorjs:core (Maven) and capacitor-swift-pm: 6.0.0 up to but not including 6.2.2, 7.0.0 up to but not including 7.6.9, 8.3.5 up to but not including 8.4.3, and 8.5.0 up to but not including 8.5.1. Versions 8.0.0 through 8.3.4 are affected and have no patched release listed.

npm ls @capacitor/android @capacitor/ios

For Swift Package Manager and Gradle projects, check the Capacitor version in Package.resolved or your Gradle dependency. Disabling CapacitorHttp does not remove the exposure.

Upgrade to a patched version, then rebuild and redistribute your app: 6.2.2, 7.6.9, 8.4.3 or 8.5.1, matching your major line.

npm install @capacitor/[email protected] @capacitor/[email protected]

There is no patched release for 8.0.0 through 8.3.4, so move to 8.4.3 or later. The patch blocks frame navigations to the proxy path and serves the proxy only when CapacitorHttp is enabled and never for a main-frame request. As a workaround, a small plugin can cancel the path: override shouldOverrideLoad(Uri url) on Android, or shouldOverrideLoad(_:) on iOS, and return true when the path starts with /_capacitor_http_interceptor_. Also sanitize user-controlled link targets.

Check app logs and any network proxy for requests to a path starting with /_capacitor_http_interceptor_ in a main-frame navigation, which legitimate fetch or XMLHttpRequest use does not produce. Look for links to that path in user content, such as chat messages or comments, stored by your backend. Check which app versions your users run, since a fix needs a rebuilt and redistributed app.

Impact

Capacitor's WebView navigation guard validated only the host and scheme of a target URL, not its path. Because the internal HTTP proxy path (/_capacitor_http_interceptor_) is served at the application's own origin, a frame navigation to it was always treated as in-app navigation and allowed.

Loading that path as a document caused the native layer to fetch an arbitrary, caller-specified URL and return the response body to the WebView at the app's own origin. Script in that response then ran with full same-origin trust: access to localStorage, cookies, and every native capability the application exposes through its registered Capacitor plugins.

The proxy handler was additionally served regardless of whether the `CapacitorHttp` plugin was enabled, so applications that never enabled CapacitorHttp were also affected.

Exploitation requires a victim to activate a link inside the application's WebView. Any Capacitor application that renders user-controlled or unsanitized links (chat messages, comments, rich-text content) is a viable delivery surface.

Both Android and iOS are affected.

Patches

Two changes on each platform:

1. The navigation guard now blocks frame navigations whose path is the internal proxy path.
2. The proxy handler is served only when CapacitorHttp is enabled, and never for a document (main frame) request.

Legitimate CapacitorHttp usage is unaffected. fetch and XMLHttpRequest are subresource requests and do not pass through the navigation guard.

Upgrade to a patched version, then rebuild and redistribute your application.

Workarounds

If you cannot upgrade immediately, note first that disabling `CapacitorHttp` is not sufficient on affected versions, because the proxy path is served regardless of that setting.

Registered plugins are consulted before the navigation guard runs, so a small plugin can block the path. On Android, override shouldOverrideLoad(Uri url) and return true when url.getPath() starts with /_capacitor_http_interceptor_. On iOS, implement shouldOverrideLoad(_:) and return true for the same path. Returning true cancels the navigation; return null/nil for all other URLs so normal navigation is unchanged.

Independently, sanitize user-controlled link targets before rendering them in the WebView.